The present invention relates generally to a fan apparency arrangement. More particularly, the present invention relates to a fan apparency arrangement for an appliance and an appliance incorporating such a fan apparency arrangement.
Appliances such as cooking ranges and wall ovens are widely used. A cooking range typically includes an oven with a front-opening access door, and at least one heating element for heating up the inside of the oven cavity. Wall ovens have a similar configuration. As is known in the art, when energized, the heating element can heat up the inside of the oven cavity to a relatively high temperature. Also as is known in the art, such cooking appliance often has a fan which is used to draw cooling air into the interior of the appliance to cool a structural component of the appliance, such as the front-opening access door, or a heat sensitive component such as an electronic control. If an appliance employs a fan for cooling, some certification institutions, such as Underwriters Laboratories Inc. (UL), require that a fan apparency device (FAD) be employed to determine or detect whether the fan is working properly.
As is known in the art, in appliances relying upon a fan for cooling airflow, when a user selects or chooses a heating operation of the appliance and turns on the appliance, the turning-on also turns on the fan. The FAD then determines or detects whether the fan is working properly. If the fan is working properly, the FAD enables the selected heating operation of the appliance to proceed. On the other hand, if the fan is not working properly, the FAD prevents the selected heating operation of the appliance from proceeding.
Various types of FADs are used to determine or detect whether the fan is working properly. The most widely used FADs are thermal switches and sail switches. A thermal switch uses the heat from the oven to heat up a bimetal member of the switch to activate the switch when the airflow from the fan is not sufficient to cool off the bimetal member. Compared with the sail switches, the thermal switches usually have a relatively slow reaction time because it uses the heat from the oven or a heat generating component of the oven to heat up the bimetal member. As a result, the existing fan apparency arrangement using a thermal switch usually has a relatively slow reaction time.
It would be desirable to provide a fan apparency arrangement, which still uses a thermal switch but which has a much faster reaction time.